For 86 episodes over six seasons on HBO, Gandolfini seared America's eyeballs with his portrayal of a New Jersey mob boss plagued by self-doubt and petty problems, yet capable of staggering and ruthless violence.

With news of his death in Italy, the world lost not only an immensely talented actor, but also a cultural icon.

But success was a long time coming for Gandolfini. He began his career playing cold-hearted mob enforcers in films like "True Romance" and "Terminal Velocity."

He kept getting cast as rough characters -- and kept excelling in the roles.

"Admirers of film acting can see him in 'Get Shorty,' 'In the Loop,' 'Welcome to the Rileys,' 'Killing Them Softly,' 'Zero Dark Thirty' and 'Not Fade Away' and find an actor who could blend tough and tender like a master," Peter Travers, host of ABC News' "Popcorn," wrote in a blog for Rolling Stone. "He didn't talk much about acting. He just did it."

As his career developed, so did his portrayal of some of society's roughest characters. In the 1996 film, "The Juror," he played a hit man with a conscience.

By the time the world met Tony Soprano in 1999, Gandolfini had become a seasoned master at bringing to life the gray areas between crime and civility, evil and humanity.

But at first, he didn't even think he was right for the role.

"I got the script and I read it and I was laughing out loud," he told "Inside the Actors Studio." "I said, 'There is no way I will be able to do this.' I really thought they would pick someone different than I ... you know suave, good looking, Mafioso-type guy ... you know, just somebody a little bit more leading-man type, basically.

"At one of the auditions, halfway through or in the middle of it, I said, 'No I'm not doing this right, I didn't prepare for this right, I'm not doing this right and I don't want to do this anymore. I want to come back and do it for you again,'" he added. "And they said, 'Oh OK,' and they let me leave and redo it and come back. People want to see you, they want something from you. ... Don't try to please them, do it for yourself."

So he did it his own way, and many critics saw that as a secret of his success as Tony Soprano. He wasn't just a homicidal mafioso, a brutal tough guy. He was, in a sense, every guy. He had problems. He was a family man in a sometimes troubled family.

Tony Soprano's journey of self-discovery, combined with his vicious mobster machinations, made the show so relentlessly watchable, so enormously influential.

"He was part of the redefining of the TV anti-hero, making sort of a monstrous figure very human by being such an unconventional leading man," TV Guide senior TV critic Matt Roush told ABC News Radio.

"James Gandolfini was probably nobody's first choice of being a major TV star," Roush added. "He's a character actor getting the role of a lifetime and becoming sort of an unexpected sex symbol. I think TV Guide back in 2005 had him 28 on the list of 50 sexiest stars of all time just because I would think just the authenticity of what he brought to the role of Tony Soprano."

"I know that's not supposed to matter when you're talking about the legacy of an actor who died too young," he said, "but when you've been up close to a guy like that and you can sense the decency in him ... it makes an impression."

Seitz interviewed Gandolfini for New Jersey's Star-Ledger newspaper just as "The Sopranos" was going on the air -- but not before the actor called him on his home phone and said he didn't think he was worthy of adulation.

"I get on the phone and he said, 'Matt, I've been thinking about this and I just don't think I want to do this interview,'" Seitz recalled. "I said, 'Why?' and he said, 'I just don't think I'm that interesting and I don't know why people would be interested in me.'"

Once the interview began, Seitz said, "He didn't want to talk about anything." So Seitz turned the conversation to acting, and Gandolfini opened up with thoughts about actors he said inspired him, including, perhaps, a surprise.

"He went on and on about Mickey Rourke," Seitz said. "He didn't want to be like Mickey Rourke. He actually wanted to be Mickey Rourke. ... He talked about Mickey Rourke the way a 9-year-old boy talks about Superman."

After "The Sopranos" ended its original run in 2007, Gandolfini looked to branch out, playing, for example, then-Defense Secretary Leon Panetta in 2012's retelling of the hunt for Osama bin Laden, "Zero Dark Thirty."

But the mob roles beckoned. He played alongside Brad Pitt in last year's "Killing Them Softly," telling ABC News' Cynthia McFadden he had to be talked into playing another tough guy.

"I didn't want to do another mob guy for a long time," he said. "I've done it for 10 years. I had no more tricks. I couldn't pull anything out of the hat for this kind of thing."

In a statement, HBO said: "We're all in shock and feeling immeasurable sadness at the loss of a beloved member of our family. He was special man, a great talent, but more importantly a gentle and loving person who treated everyone no matter their title or position with equal respect."

Now, he is gone -- leaving behind a wife and two children, including an 8-month-old girl.

But, like all iconic roles, Tony Soprano lives on -- and, through him, the man who brought him to life.